A gas turbine engine generally includes a compressor section, a combustion section, and a turbine section. The compressor section progressively increases the pressure of air entering the gas turbine engine and supplies this compressed air to the combustion section. The compressed air and a fuel (e.g., natural gas) mix within the combustion section and burn in a combustion chamber to generate high pressure and high temperature combustion gases. The combustion gases flow from the combustion section into the turbine section where they expand to produce work. For example, expansion of the combustion gases in the turbine section may rotate a rotor shaft connected to a generator to produce electricity.
In general, gas turbine engine performance and efficiency may be improved by increased combustion gas temperatures. Non-traditional high temperature materials, such as alumina-based or silicon carbide-based ceramic matrix composite (CMC) materials, are more commonly being used for various components within gas turbine engines. In particular, there is strong interest in replacing metal alloy components within the combustion and turbine sections with CMC materials. CMC materials can withstand higher operating temperatures than nickel-based super alloys and most refractory alloys. CMC materials require less cooling than nickel super alloys enabling higher turbine efficiencies. In certain instances, CMC materials may also reduce the structural demands on associated metal hardware, such as a metallic disk mated to a CMC rotor blade.
Although CMC components may withstand more extreme temperatures than components formed from traditional materials, certain CMC components still may require cooling features. For example, these CMC components may define various cooling passages extending therethrough. Cooling air may flow through these cooling passages, thereby cooling the CMC component. Nevertheless, the conventional methods of forming cooling passages in CMC components may result in cooling passages that limit the service life of the CMC component.